/*
 *  textbox.c -- implements the text box
 *
 *  ORIGINAL AUTHOR: Savio Lam (lam836@cs.cuhk.hk)
 *  MODIFIED FOR LINUX KERNEL CONFIG BY: William Roadcap (roadcap@cfw.com)
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "dialog.h"

static void back_lines(int n);
static void print_page(WINDOW* win, int height, int width, update_text_fn
                       update_text, void* data);
static void print_line(WINDOW* win, int row, int width);
static char* get_line(void);
static void print_position(WINDOW* win);

static int hscroll;
static int begin_reached, end_reached, page_length;
static char* buf;
static char* page;

/*
 * refresh window content
 */
static void refresh_text_box(WINDOW* dialog, WINDOW* box, int boxh, int boxw,
                             int cur_y, int cur_x, update_text_fn update_text,
                             void* data)
{
	print_page(box, boxh, boxw, update_text, data);
	print_position(dialog);
	wmove(dialog, cur_y, cur_x);	/* Restore cursor position */
	wrefresh(dialog);
}


/*
 * Display text from a file in a dialog box.
 *
 * keys is a null-terminated array
 * update_text() may not add or remove any '\n' or '\0' in tbuf
 */
int dialog_textbox(const char* title, char* tbuf, int initial_height,
                   int initial_width, int* keys, int* _vscroll, int* _hscroll,
                   update_text_fn update_text, void* data)
{
	int i, x, y, cur_x, cur_y, key = 0;
	int height, width, boxh, boxw;
	WINDOW* dialog, *box;
	bool done = false;

	begin_reached = 1;
	end_reached = 0;
	page_length = 0;
	hscroll = 0;
	buf = tbuf;
	page = buf;	/* page is pointer to start of page to be displayed */

	if(_vscroll && *_vscroll) {
		begin_reached = 0;

		for(i = 0; i < *_vscroll; i++)
			get_line();
	}

	if(_hscroll)
		hscroll = *_hscroll;

do_resize:
	getmaxyx(stdscr, height, width);

	if(height < TEXTBOX_HEIGTH_MIN || width < TEXTBOX_WIDTH_MIN)
		return -ERRDISPLAYTOOSMALL;

	if(initial_height != 0)
		height = initial_height;
	else if(height > 4)
		height -= 4;
	else
		height = 0;

	if(initial_width != 0)
		width = initial_width;
	else if(width > 5)
		width -= 5;
	else
		width = 0;

	/* center dialog box on screen */
	x = (getmaxx(stdscr) - width) / 2;
	y = (getmaxy(stdscr) - height) / 2;

	draw_shadow(stdscr, y, x, height, width);

	dialog = newwin(height, width, y, x);
	keypad(dialog, TRUE);

	/* Create window for box region, used for scrolling text */
	boxh = height - 4;
	boxw = width - 2;
	box = subwin(dialog, boxh, boxw, y + 1, x + 1);
	wattrset(box, dlg.dialog.atr);
	wbkgdset(box, dlg.dialog.atr & A_COLOR);

	keypad(box, TRUE);

	/* register the new window, along with its borders */
	draw_box(dialog, 0, 0, height, width,
	         dlg.dialog.atr, dlg.border.atr);

	wattrset(dialog, dlg.border.atr);
	mvwaddch(dialog, height - 3, 0, ACS_LTEE);

	for(i = 0; i < width - 2; i++)
		waddch(dialog, ACS_HLINE);

	wattrset(dialog, dlg.dialog.atr);
	wbkgdset(dialog, dlg.dialog.atr & A_COLOR);
	waddch(dialog, ACS_RTEE);

	print_title(dialog, title, width);

	print_button(dialog, gettext(" Exit "), height - 2, width / 2 - 4, TRUE);
	wnoutrefresh(dialog);
	getyx(dialog, cur_y, cur_x);	/* Save cursor position */

	/* Print first page of text */
	attr_clear(box, boxh, boxw, dlg.dialog.atr);
	refresh_text_box(dialog, box, boxh, boxw, cur_y, cur_x, update_text,
	                 data);

	while(!done) {
		key = wgetch(dialog);

		switch(key) {
			case 'E':	/* Exit */
			case 'e':
			case 'X':
			case 'x':
			case 'q':
			case '\n':
				done = true;
				break;

			case 'g':	/* First page */
			case KEY_HOME:
				if(!begin_reached) {
					begin_reached = 1;
					page = buf;
					refresh_text_box(dialog, box, boxh, boxw,
					                 cur_y, cur_x, update_text,
					                 data);
				}

				break;

			case 'G':	/* Last page */
			case KEY_END:

				end_reached = 1;
				/* point to last char in buf */
				page = buf + strlen(buf);
				back_lines(boxh);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case 'K':	/* Previous line */
			case 'k':
			case KEY_UP:
				if(begin_reached)
					break;

				back_lines(page_length + 1);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case 'B':	/* Previous page */
			case 'b':
			case 'u':
			case KEY_PPAGE:
				if(begin_reached)
					break;

				back_lines(page_length + boxh);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case 'J':	/* Next line */
			case 'j':
			case KEY_DOWN:
				if(end_reached)
					break;

				back_lines(page_length - 1);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case KEY_NPAGE:	/* Next page */
			case ' ':
			case 'd':
				if(end_reached)
					break;

				begin_reached = 0;
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case '0':	/* Beginning of line */
			case 'H':	/* Scroll left */
			case 'h':
			case KEY_LEFT:
				if(hscroll <= 0)
					break;

				if(key == '0')
					hscroll = 0;
				else
					hscroll--;

				/* Reprint current page to scroll horizontally */
				back_lines(page_length);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case 'L':	/* Scroll right */
			case 'l':
			case KEY_RIGHT:
				if(hscroll >= MAX_LEN)
					break;

				hscroll++;
				/* Reprint current page to scroll horizontally */
				back_lines(page_length);
				refresh_text_box(dialog, box, boxh, boxw, cur_y,
				                 cur_x, update_text, data);
				break;

			case KEY_ESC:
				if(on_key_esc(dialog) == KEY_ESC)
					done = true;

				break;

			case KEY_RESIZE:
				back_lines(height);
				delwin(box);
				delwin(dialog);
				on_key_resize();
				goto do_resize;

			default:
				for(i = 0; keys[i]; i++) {
					if(key == keys[i]) {
						done = true;
						break;
					}
				}
		}
	}

	delwin(box);
	delwin(dialog);

	if(_vscroll) {
		const char* s;

		s = buf;
		*_vscroll = 0;
		back_lines(page_length);

		while(s < page && (s = strchr(s, '\n'))) {
			(*_vscroll)++;
			s++;
		}
	}

	if(_hscroll)
		*_hscroll = hscroll;

	return key;
}

/*
 * Go back 'n' lines in text. Called by dialog_textbox().
 * 'page' will be updated to point to the desired line in 'buf'.
 */
static void back_lines(int n)
{
	int i;

	begin_reached = 0;

	/* Go back 'n' lines */
	for(i = 0; i < n; i++) {
		if(*page == '\0') {
			if(end_reached) {
				end_reached = 0;
				continue;
			}
		}

		if(page == buf) {
			begin_reached = 1;
			return;
		}

		page--;

		do {
			if(page == buf) {
				begin_reached = 1;
				return;
			}

			page--;
		} while(*page != '\n');

		page++;
	}
}

/*
 * Print a new page of text.
 */
static void print_page(WINDOW* win, int height, int width, update_text_fn
                       update_text, void* data)
{
	int i, passed_end = 0;

	if(update_text) {
		char* end;

		for(i = 0; i < height; i++)
			get_line();

		end = page;
		back_lines(height);
		update_text(buf, page - buf, end - buf, data);
	}

	page_length = 0;

	for(i = 0; i < height; i++) {
		print_line(win, i, width);

		if(!passed_end)
			page_length++;

		if(end_reached && !passed_end)
			passed_end = 1;
	}

	wnoutrefresh(win);
}

/*
 * Print a new line of text.
 */
static void print_line(WINDOW* win, int row, int width)
{
	char* line;

	line = get_line();
	line += MIN(strlen(line), hscroll);	/* Scroll horizontally */
	wmove(win, row, 0);	/* move cursor to correct line */
	waddch(win, ' ');
	waddnstr(win, line, MIN(strlen(line), width - 2));

	/* Clear 'residue' of previous line */
#if OLD_NCURSES
	{
		int x = getcurx(win);
		int i;

		for(i = 0; i < width - x; i++)
			waddch(win, ' ');
	}
#else
	wclrtoeol(win);
#endif
}

/*
 * Return current line of text. Called by dialog_textbox() and print_line().
 * 'page' should point to start of current line before calling, and will be
 * updated to point to start of next line.
 */
static char* get_line(void)
{
	int i = 0;
	static char line[MAX_LEN + 1];

	end_reached = 0;

	while(*page != '\n') {
		if(*page == '\0') {
			end_reached = 1;
			break;
		} else if(i < MAX_LEN)
			line[i++] = *(page++);
		else {
			/* Truncate lines longer than MAX_LEN characters */
			if(i == MAX_LEN)
				line[i++] = '\0';

			page++;
		}
	}

	if(i <= MAX_LEN)
		line[i] = '\0';

	if(!end_reached)
		page++;		/* move past '\n' */

	return line;
}

/*
 * Print current position
 */
static void print_position(WINDOW* win)
{
	int percent;

	wattrset(win, dlg.position_indicator.atr);
	wbkgdset(win, dlg.position_indicator.atr & A_COLOR);
	percent = (page - buf) * 100 / strlen(buf);
	wmove(win, getmaxy(win) - 3, getmaxx(win) - 9);
	wprintw(win, "(%3d%%)", percent);
}
